The present invention relates to signal safety of a transport system for performing transportation by a train moving on a rail, that is, railway and city traffic such as monorail, light rail transit (LRT), automated guided train (AGT) etc.
In a railway system using narrow-area wireless communication means, as a method of detecting a railway train, such as transponder, valise etc which are used as small-sized communication units installed on the ground and on a train (hereinafter, description will be made by taking the transponder as an example of the narrow-area wireless communication means), presence/absence of the train is judged by performing communications of the train ID between the ground and the train using the transponders discretely arranged along the rail. That is, the presence/absence of the train is judged through a check-in-check-out method in which receiving of the train ID by a transponder arranged in another region is regarded the train as not being present in a region having a transponder which the same train ID has previously been received from. This is that a confirmation of presence at one place leads an evidence of absence at the other places.
The details will be described below. Transponders for performing communication between a train and the ground are arranged on the train and on the ground. A block section is a section in which only one train is allowed to be present, but a set of transponder is arranged there in a conventional system(refer to patent reference 1 as shown later). It is provided that a train B bound for a station a is waiting for a train A to depart from the station a now. In the check-in-check-out method, presence/absence of the train in a block section is judged through the following processes. The train B departs from the station a, and enters into a neighboring block section, but the block section of the station a is not judged to be absent. It is not judged that there is no train in the block section of the station a, until a transponder provided in the station b detects that the train A reaches a neighboring block section. That is, the train detecting method is that the train A reaches the station b, and then, by receiving a signal of absence of train in the block section of the station a, the train B starts to proceed to the station a.
Because in this method, only one set of transponder is arranged in one block section (the train has one in the front and another in the rear of the train), absence of the train in the block section of a station can not be judged until the train reaches the neighboring station. In order to solve this problem, a configuration of transponders disclosed in non-patent reference 1 as shown later is employed. In this configuration, by arranging transponders individually at the entrance and at the exit of a block section, entering of a train departing from a station into the neighboring block section is promptly detected by the transponder provided at the entrance of the neighboring block section. More specifically, departure of the train A from the station a is certainly detected by the fact that the train A departing from the station a passes through the transponder provided in the exit side of the station, the following train B can promptly proceed to the station a by setting the block section of the station a to absent.
[Patent Reference 1]
Japanese Patent Application Laid-Open No. 3-292255 (all pages)
[Non-patent Reference 1]
“Development of a block control system for IMTS”, Transaction of The 2001 Joint symposium of Railway Technologies, pp. 255–258, published in 2001.